For women under 30, the Pap smear is still the best option, but testing every three years is all right. The recommendations are based on a now-solid body of evidence showing that almost all cases of cervical cancer are caused by the human papillomavirus and that the HPV test is the best way to find evidence that the virus is causing the damage that can lead to cancer.

The guidelines, in short:

Women ages 21-29 should get a Pap smear every three years

Women ages 30-65 can get an HPV test every five years, or a Pap test every three years, or a combination every five years

Women over 65 who have had recent clear tests probably don’t need testing any more

Women under 21 probably do not need testing.

While the new guidelines may seem confusing, they are simpler than the last batch, said Dr. Kathleen Schmeler, a cervical cancer specialist at the University of Texas MD Anderson Cancer Center.

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She said the guidelines may make it easier for women in areas with fewer doctors or clinics to get tested.

“The new guidelines are not at all confusing to us physicians, since they are very similar to our usual practice from 2012,” said Dr. Ranit Mishori, a professor of family medicine at Georgetown University.

“I do not find that the longer interval is confusing to women — many, in fact, are relieved that they don't have to undergo this procedure every year and are thankful to find out that they can wait three or five years before they need to get the next one.”

"We found that regular screening with any method will lead to lower cervical cancer rates," said Joy Melnikow, director of the Center for Healthcare Policy and Research at the University of California, Davis, who led a study showing that the HPV test is effective.

"In the U.S., where most women are not part of an organized screening program, our biggest challenge is reaching women who have not been screened."

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If the body, for whatever reason, does not clear the HPV infection, that is worrisome.

A Pap smear will find precancerous changes in the cervix without frightening women who simply have a fresh HPV infection that won’t necessarily cause trouble.

But by the time a woman is 30, the virus has had time to potentially take hold in the tissue and start causing the damage that can lead to cancer. The HPV test will find the virus if it is still lingering, or if it has resurfaced for some reason.

“It is not like you get HPV and then you get cancer,” Schmeler said. It only happens in a few people, and the process usually takes years.

For now, a woman’s experience at the clinic will be the same whether she has a Pap or an HPV test. It still requires getting into the stirrups.